A. Field of the Invention
The invention described herein relates to methods and devices for providing a signal peak detector having rapid response to signal envelope variations while reducing ripple due to low frequency data components.
B. Description of the Related Art
In communication systems, variations of the amplitude of the received signals require continuing adjustments of the receiver's gain in order to maintain a relatively constant output signal. For example, power transients caused by switching devices may create power fluctuations as channels are added or dropped. A variable gain amplifier (VGA) with automatic gain control (AGC) is commonly used to automatically maintain a constant signal level at the output of the analog front end of the receiver. AGC systems typically measure the peak value of the waveform of the VGA output to detect any power fluctuations.
Peak detectors are typically used to measure the peak value of the fluctuating electrical signals. It is desirable to have a peak detector that is capable of tracking amplitude variations due to undesired power fluctuations rather than to interpret amplitude variations that are due to data signal components. Typically the bandwidth of a peak detector is sufficiently low so that frequency components associated with the data signaling is not passed through the peak detector.